3GPP Long Term Evolution, LTE, is the fourth-generation mobile communication technologies standard developed within the 3rd Generation Partnership Project, 3GPP, to improve the Universal Mobile Telecommunication System, UMTS, standard to cope with future requirements in terms of improved services such as higher data rates, improved efficiency, and lowered costs. The Universal Terrestrial Radio Access Network, UTRAN, is the, RAN, Radio Access Network of a UMTS and Evolved UTRAN, E-UTRAN, is the RAN of an LTE system.
In the future, new radio coordination features are planned for LTE. Examples of new radio coordination features are CoMP, Coordinated MultiPoint, ABS, Up-link and/or down-link Almost Blank Sub-frames, RPS, Reduced Power Sub-frames, eICIC, Enhanced Inter-Cell Interference Coordination. The different radio coordination features can be categorized in three different groups, namely; flexible, tight and very tight coordination features. The different radio coordination features all put different levels of requirements on the radio access transport network to be able to use these radio coordination features. As an example the delay required for different radio coordination functions varies between sub 1 millisecond to 100 milliseconds. Similar requirements are placed for synchronization and for bandwidth in the radio access transport network. The radio access transport network handles data traffic between the radio base stations and between the radio base stations and the core network.
Today's RAN's lack information on the radio access transport network characteristics, e.g. characteristics between RBS, Radio Base Station, neighbors as well as between RBS and S/PDN-GW, Serving Packet Data Network-Gateway, and the RNC, Radio Network Controller. It is problematic for the RAN to select the optimal radio coordination features when lacking knowledge of radio access transport network characteristics and synchronization accuracy. This results in sub optimal use of resources in the RAN as well as in the radio access transport network, and in the end non-optimal end-user performance.
Thus, the RBS, which decides what radio coordination features to use, has no or very little information of radio access transport network characteristics, e.g. if the synchronization method is accurate enough or if the delay and bandwidth between neighboring RBSs is sufficient to be used for a specific radio coordination feature. Active measurements like TWAMP/BART, Two-Way Active Measurement Protocol/Bandwidth Available in Real Time, does not have access to the real radio access transport network characteristics, instead it tries to estimate the radio access transport network characteristics based on injecting test traffic.
IETF, Internet Engineering Task Force, has released several drafts in the area of an application I2RS, Interface to Routing Systems, e.g. https://datatracker.ietf.org/wg/i2rs. The architecture of I2RS allows an application to query and modify the state of the transport network. The architecture describes requirements, and the draft “Use Cases of I2RS in Mobile Backhaul Network, https://datatracker.ietf.org/wg/i2rs, describes use cases for mobile backhaul and the radio access transport network.
Presently, the RBS, which decides what radio coordination features to use, has no or very little information of the radio access transport network conditions. There is therefore a need for an improved solution for determining radio coordination features, which solution solves or at least mitigates at least one of the above mentioned problems.